Field
Embodiments of the disclosure relate generally to the field of vectoring of jet engine nozzle exhaust and more particularly to embodiments for inducing shockless flow separation in the divergent section of an exhaust nozzle to asymmetrically alter the effective divergence angle of the nozzle walls, thus creating thrust vectoring.
Background
Vectoring of jet engine nozzle exhaust for added aerodynamic control of aircraft has been employed in various designs. With additional requirements for increased maneuverability and performance of modern jet aircraft, vectored thrust systems have become highly important in achieving overall performance goals. The thrust vectoring methods in past systems can generally be categorized in two groups: mechanical and fluidic. Mechanical systems often use deflecting surfaces or gimballing of the entire nozzle to physically direct the flow in a desired direction. Fluidic systems generally fall into two subcategories: shock vectoring and sonic line skewing. Shock vectoring schemes inject flow into the divergent section of the nozzle such that a shock wave is generated in the supersonic flow thereby turning the flow. Sonic line skewing can be achieved by injecting flow near the throat of the nozzle and thus “skewing” the throat to direct flow at an angle through the divergent section.
Mechanical systems are heavy due to the requirements for large control surfaces and actuators. Shock vectoring typically requires large amounts of injection to generate a sufficiently strong shock to alter the flow direction. Large amounts of injected flow are not preferable due to the performance impact on the engine to supply the large amounts of secondary flow for injection (flow that could otherwise be used to produce thrust). Additionally, the strong shock wave created in the divergent section reduces thrust. Sonic line skewing requires intricate nozzle inner mold line shaping to assure the skewed throat is the same area as the undisturbed throat thus maintaining a constant mass flow through the duct across its operating envelope. Sonic line skewing also requires large amounts of injected flow.
It is therefore desirable to avoid the weight penalties of mechanical thrust vectoring systems by providing a fluidic thrust vectoring using less flow injection than current fluidic systems to achieve desired vector angles. It is also desirable to provide thrust vectoring which does not impact the nozzle throat area, thus easily maintaining the engine mass flow. Additionally, it is desirable to provide thrust vectoring which is simple to implement and provides an effective fluidic vectoring solution while minimizing thrust loses.